/* 基础样式重置 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: '微软雅黑', 'PingFang SC', sans-serif;
}

body {
    line-height: 1.6;
    color: #333;
    background: #fff;
    transition: background 0.3s, color 0.3s;
}

body.dark-mode {
    background: #1a1a1a;
    color: #f0f0f0;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 导航栏样式 */
.header {
    background: #fff;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
    transition: background 0.3s;
}

body.dark-mode .header {
    background: #333;
    box-shadow: 0 2px 10px rgba(0,0,0,0.3);
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
}

.logo {
    font-size: 24px;
    font-weight: bold;
    color: #0078D7;
    text-decoration: none;
}

.nav-list {
    display: flex;
    list-style: none;
    gap: 30px;
}

.nav-list a {
    color: #333;
    text-decoration: none;
    font-size: 16px;
    transition: color 0.3s;
}

body.dark-mode .nav-list a {
    color: #f0f0f0;
}

.nav-list a:hover {
    color: #0078D7;
}

.mobile-menu {
    display: none;
    font-size: 24px;
    background: none;
    border: none;
    cursor: pointer;
}

/* 首页大图 - 适配暗色模式 */
.hero {
    background: #fff;
    background-size: cover;
    background-position: center;
    height: 80vh;
    display: flex;
    align-items: center;
    color: #222;
    margin-top: 70px;
    transition: background 0.3s, color 0.3s;
}

body.dark-mode .hero {
    background: #2a2a2a;
    color: #f0f0f0;
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 20px;
}

.hero p {
    font-size: 1.2rem;
    margin-bottom: 30px;
    max-width: 600px;
    color: #444;
}

body.dark-mode .hero p {
    color: #ccc;
}

/* 统一按钮样式 - 圆角矩形 */
.cta-button, .join-btn {
    display: inline-block;
    background: #0078D7;
    color: white;
    padding: 12px 30px;
    border-radius: 8px;
    text-decoration: none;
    font-weight: bold;
    transition: background 0.3s;
    border: none;
    cursor: pointer;
}

.cta-button:hover, .join-btn:hover {
    background: #005A9E;
}

.join-btn {
    background: transparent;
    color: #0078D7;
    border: 2px solid #0078D7;
}

.join-btn:hover {
    background: #0078D7;
    color: white;
}

/* 核心服务 */
.services {
    padding: 80px 0;
    background: #F0F7FF;
    transition: background 0.3s;
}

body.dark-mode .services {
    background: #2a2a2a;
}

.services h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 50px;
    color: #333;
}

body.dark-mode .services h2 {
    color: #f0f0f0;
}

.service-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.card {
    background: white;
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 3px 15px rgba(0,0,0,0.1);
    text-align: center;
    transition: transform 0.3s, background 0.3s;
}

body.dark-mode .card {
    background: #333;
    box-shadow: 0 3px 15px rgba(0,0,0,0.3);
}

.card:hover {
    transform: translateY(-10px);
}

.card .icon {
    font-size: 48px;
    margin-bottom: 20px;
    display: block;
}

.card h3 {
    font-size: 1.5rem;
    margin-bottom: 15px;
    color: #0078D7;
}

/* 活动列表 */
.activities {
    padding: 80px 0;
}

.activities h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 50px;
    color: #333;
}

body.dark-mode .activities h2 {
    color: #f0f0f0;
}

.activity-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
}

.activity-card {
    background: white;
    padding: 25px;
    border-radius: 10px;
    box-shadow: 0 3px 15px rgba(0,0,0,0.1);
    transition: background 0.3s;
}

body.dark-mode .activity-card {
    background: #333;
    box-shadow: 0 3px 15px rgba(0,0,0,0.3);
}

.activity-card h3 {
    font-size: 1.4rem;
    margin-bottom: 15px;
    color: #0078D7;
}

.time {
    color: #666;
    font-size: 0.9rem;
    margin-bottom: 10px;
}

body.dark-mode .time {
    color: #999;
}

.desc {
    color: #444;
    margin-bottom: 20px;
}

body.dark-mode .desc {
    color: #ccc;
}

/* 底部信息 */
.footer {
    background: #333;
    color: white;
    padding: 60px 0 20px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-section h4 {
    font-size: 1.3rem;
    margin-bottom: 20px;
    color: #0078D7;
}

.footer-section p {
    color: #ccc;
    margin-bottom: 10px;
}

.social-links a {
    color: #ccc;
    text-decoration: none;
    margin-right: 15px;
}

.copyright {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid #444;
    color: #999;
    font-size: 0.9rem;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .nav-list {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 20px;
        box-shadow: 0 5px 10px rgba(0,0,0,0.1);
    }

    body.dark-mode .nav-list {
        background: #333;
    }

    .nav-list.active {
        display: flex;
    }

    .nav-list li {
        margin: 10px 0;
    }

    .mobile-menu {
        display: block;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    .service-cards,
    .activity-list {
        grid-template-columns: 1fr;
    }
}

/* 深色模式切换按钮 */
.theme-toggle {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: #0078D7;
    color: white;
    border: none;
    border-radius: 50%;
    width: 50px;
    height: 50px;
    font-size: 20px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.2);
    transition: background 0.3s;
}

.theme-toggle:hover {
    background: #005A9E;
}